Learning science helps children to develop ways of understanding the world around them. For this they have to build up concepts which help them link their experiences together; they must learn ways of gaining and organizing information and of applying and testing ideas. This contributes not only to children"s ability to make better sense of things around them, but prepares them to deal more effectively with wider decision-making and problem-solving in their lives. Science is as basic a part of education as numeracy and literacy; it daily becomes more important as the complexity of technology increases and touches every part of our lives. Learning science can bring a double benefit because science is both a method and a set of ideas; both a process and a product. The process of science provide a way of finding out information, testing ideas and seeking explanations. The products of science are ideas which can be applied in helping to understand new experiences. The word "can" is used advisedly here; it indicates that there is the potential to bring these benefits but no guarantee that they will be realized without taking the appropriate steps. In learning science the development of the process side and the product side must go hand in hand; they are totally interdependent. This has important implications for the kinds of activities children need to encounter in their education. But before pursuing these implications, there are still two further important points which underline the value of including science in primary education. The first is that whether we teach children science or not, they will be developing ideas about the world around from their earliest years. If these ideas are based on casual observation, non-investigated events and the acceptance of hearsay, then they are likely to be non-scientific, "everyday" ideas. There are plenty of such ideas around for children to pick up. My mother believed (and perhaps still does despite my efforts) that if the sun shines through the window on to the fire it puts the fire out, that cheese maggots (a common encounter in her youth when food was sold unwrapped)are made of cheese and develop spontaneously from it, that placing a lid on a pan of boiling water makes it boil at a lower temperature, that electricity travels more easily if the wires are not twisted. Similar myths still abound and no doubt influence children"s attempts to make sense of their experience. As well as hearsay, left to themselves, children will also form some ideas which seem unscientific; for example, that to make something move requires a force but to stop it needs no force. All these ideas could easily be put to the test; children"s science education should make children want to do it. Then they not only have the chance to modify their ideas, but they learn to be skeptical about so-called "truths until these have been put to the test. Eventually they will realize that all ideas are working hypotheses which can never be proved right, but are useful as long as they fit the evidence of experience and experiment. The importance of beginning this learning early in children"s education is twofold. On the one hand the children begin to realize that useful ideas must fit the evidence; on the other hand they are less likely to form and to accept everyday ideas which can be shown to be indirect conflict with evidence and scientific concepts. There are research findings to show that the longer the non-scientific ideas have been held, the more difficult they are to change. Many children come to secondary science, not merely lacking the scientific ideas they need, but possessing alternative ideas which are a barrier to understanding their science lessons. The second point about starting to learn science, and to learn scientifically, at the primary level is connected with attitudes to the subject. There is evidence that attitudes to science seem to be formed earlier than to most other subjects and children tend to have taken a definite position with regard to their liking of the subject by the age of 11 to 12. Given the remarks just made about the clash between the non-scientific ideas that many children bring to their secondary science lessons and the scientific ideas they are assumed to have, it is not surprising that many find science confusing and difficult. Such reactions undoubtedly affect their later performance in science. Although there is a lesson here for secondary science, it is clear that primary science can do much to avoid this crisis at the primary/secondary interface.